The purpose of our research is to analyze sensory transduction in the cyclic AMP chemosensory system of the lower eukaryote Dictyostelium. Our goals are (1) to isolate sensory mutants to define by genetic means the number of components in this system, (2) to determine conclusively if several presumptive thermo-sensitive mutants are, indeed, ts for sensory behavior, and (3) to establish ways for analyzing the plasma membrane of Dictyostelium so that plasma membrane-bound components of this sensory system can be identified. We shall also investigate the sensory behavior or Polysphondylium violaceum.